We observe a significant improvement of the spectrum for all polynomial orders. For all choices of \(c\) , the eigenfrequencies in the high frequencies range, the last \(25\%\)  of the spectrum, are suppressed. In many cases, the result is an underprediction of the analytical values, which is not a problem: the high frequencies do generally not contribute to the fidelity of dynamics simulations [1]}, but do limit their critical time step. In the lowest \(25\%-50\%\)  of the spectrum we observe that the mass scaling does not negatively affect the numerically computed eigenfrequencies, as can be seen clearly in the semi-log inset figures. This is crucial, since these eigenfunction-eigenfrequency pairs typically dominate the system response. For the intermediate range of frequencies, i.e. until roughly \(75\%\) , the normalized numerical eigenfrequencies are pushed closer towards the desired value of 1, improving the overall accuracy and smoothness of the discrete spectra.
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